ASNE Day 2016 - Technical Paper Session 5 : Thursday, March 3, 2016 1330-1500
Current Trends in Naval Applications
Authors: Mohamed Belkhayat, Marie Lawson, Kyle Maynard, and Zareh Soghomonian
Title: Load Measurement via Remote Sensor Retro-Fit, and Algorithm Development for Evaluation of Ramp Rate and Pulsed Power in a High-Voltage Industrial Environment
A practical and complete methodology has been developed for evaluating compliance of a nominally a dynamic load, in a 13.8kV, 60Hz, three-phase active industrial environment, against requirements governing the electrical load’s ramp rate and pulsation. The objective in developing the methodology was to complement the discretizing effect of the system sampling rate and to balance the priorities of protecting power generation assets against excessive ramp rate, while also avoiding declaration of spurious deviations due to noise or ripple. The methodology presented has broad applicability to validating integration of large electrical loads to a host power architecture.
Protection of power generation assets was a central concern in developing the measurement and evaluation methodology. Understanding the physics behind throttle valve movements in a steam-driven turbine generator, as well as the physics operating in a diesel generator were criteria in design of signal filters in the software and in deriving detailed requirements from the top-level specifications.
Pulsed load definitions and pass/fail criteria are drawn from MIL-STD-1399/300B, but the specification leaves open questions regarding how to numerically evaluate a pulsed load or a load’s ramp rate against the provided thresholds. In the case of a pulsed load, an algorithm has been developed to handle initialization; monitor instantaneous power against a running baseline; determine if a pulse is occurring; measure pulse magnitude; and time-out in the case of a shift of baseline. The algorithm will evaluate detected pulses’ measured magnitudes against the specification limits. Key scenarios were defined to explore the boundaries of the algorithm’s behavior at a rigorous level of detail.
Power ramp rate requirements have been drawn from an application-specific electrical interface requirement derived from MIL-STD-1399/300B that specifies a simple pass/fail limit of power delta over time. An algorithm has been developed to handle initialization; calculate a moving average which is filtered sufficiently to provide immunity to noise and normal ripple without excessively reducing sensitivity; and calculate an implied slope of ramp rate over a moving time window derived from the requirement. The implementation of the ramp rate evaluation window was selected after a comparison of various possible strategies. In addition, the practical challenges of synchronous data processing in the software versus asynchronous data transmittal from the data acquisition hardware were explored and resolved.
MATLAB Simulink/SimPower was used to develop a physics-based validation model of the power distribution system which included the load of interest and the transformer serving it, thus providing a validation method for the entire process. The simulation results are discussed and a conclusion is made.
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